From 12 Finger Swaps to Zero: SusGrip-3F for High-Mix Low-Volume Machine Tending

Problem Overview

Sumitomo Heavy Industries (Vietnam) Co., Ltd. runs a machine-tending line for large shell components, with two cobot arms carrying two three-finger pneumatic grippers each.

The line handles only three shell sizes, but each runs in small batches, so sizes change often. Every size change meant replacing all 12 fingers, each numbered to a set position on its gripper.

Each changeover stopped the line for the finger swap and a grip check, and could only be done by an experienced technician. A single misplaced finger risked a failed or inconsistent grip. With small batches, this cost was incurred at every changeover.

Apicoo's Solution

Apicoo replaced the four pneumatic grippers with four SusGrip-3F units. Each unit is fitted with custom fingers for internal gripping, and each gripper covers all three shell sizes without changing fingers.

A size change is now made in software: stroke, gripping force and speed for each size are saved as a stored setting, and the operator selects it

How SusGrip Solved the Problem

Pneumatic grippers have real strengths: at common sizes they often deliver more force for their size, they cost less per unit, and the factory already had compressed air, so no additional infrastructure was needed.

The deciding factor for switching was changeover cost, driven by two things: time and people. Every size change stopped the line for a finger swap, and only an expert could do it. On an automated line, any step that still needs a person is costly: the line waits for them, and their skill has to be paid for.

A misplaced finger risked a failed grip

Each swap needed an expert and stopped the line

Heavy, oil-coated shells needed higher force and more friction

SusGrip-3F's custom fingertips - sized for a larger contact surface and secure inside grip - shown coated in coolant oil after continuous operation on the line.

High cycle count required a repeatable grip position

Every grip had to be confirmed

Before / After

Deep-Dive: Why High-Mix Production Is Driving a Shift from Pneumatic to Electric Gripper

What changes when a line goes high-mix

In stable production, a gripper is set up once and repeats the same cycle for weeks. When batches shrink and sizes change often, the cost that decides the choice of gripper moves from the gripper itself to the changeover. This line has only three SKUs, but small batches made it high-mix in practice

Changeover steps for a size change: pneumatic gripper vs. electric gripper (SusGrip-3F).

A pneumatic changeover has up to four steps: swap the fingers, adjust the pressure, test the grip, and restart. Pressure only needs adjusting when parts vary greatly. On the Sumitomo line, the shells are all large and similar enough in size and weight to share one pressure setting, so that step was skipped. The finger swap and grip test remained manual, and the swap needed an expert.

With an electric gripper like SusGrip-3F, stroke and force are stored settings and the gripper confirms its own grip, so the same change takes two steps: select the setting and restart.

Fewer steps means a shorter line stop and no step that depends on an expert, and that saving repeats at every size change. How much this saving is worth depends on three questions:

• Does a size change require new fingers? If all sizes fit within one stroke, the same fingers handle them all and there is little to save. If they do not, every size change means swapping fingers.
• How often do sizes change? A finger swap means a stopped line. A line that changes size once a month pays that cost once a month. A line running small batches pays it with every batch.
• How costly is each changeover? A longer swap keeps the line stopped longer, which means more lost output. If the swap needs a skilled technician, it also adds the cost of employing one, and the line may have to wait until they are available.

On the Sumitomo line, all three pointed the same way: three diameters that no single finger set could cover, small batches, and 12 numbered fingers that needed an expert.

Why electric can now take over

Electric grippers offer more than a faster changeover. Position, force and speed are programmable and stored per part. Built-in position feedback confirms the part, checks its size and detects a drop, where pneumatic grippers typically need add-on sensors or servo valves. Grip force stays consistent regardless of air pressure, hose length or temperature, and no compressed air is needed.

These advantages only matter if the electric gripper first does everything the pneumatic one was already doing well. A gripper that changes size in software but cannot hold the part securely is no improvement. 

On this line, the pneumatic grippers were already:

• Holding heavy, oily parts securely: Each shell weighs about 2 kg and is coated in coolant oil, gripped from the inside. 
• Reaching the largest sizes. The shells run up to 230 mm. 
• Running reliably in the cell. The line runs 3 shifts a day in coolant oil.
• Keeping the grip position consistent. At about 1,800 grip cycles per shift, the grip has to repeat from the first cycle to the last.

That is what drives the shift: not that electric grippers became more flexible, but that they can now match pneumatic in demanding applications such as CNC machine tending.

Where pneumatic still fits

Pneumatic grippers keep real strengths: a lower purchase price, high force for their size, robustness, fast cycles and simple maintenance. Where parts do not change often, those strengths still decide. Pneumatic remains the practical choice, for example, on:

• Lines that run one part for long periods, or several sizes that fit within one stroke, so fingers rarely need changing.
• High-speed pick-and-place, where the shortest cycle time matters most.
• Compact cells that need high grip force from a small, light gripper.
• Simple gripping tasks that need no grip data or fine force control, in plants with compressed air already in place.

The shift therefore happens application by application, not across a whole plant at once. Our comparison of electric and pneumatic grippers for high-mix CNC machine tending covers these trade-offs in full.

Talk to Apicoo About This Application

If your facility has a CNC machine tending application - high-mix, multi-SKU, or harsh environment - contact us. We'll walk through the application with you.

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